By law, an expense is allowable as a deduction only if it is incurred ‘wholly and exclusively’ for business purposes. It doesn’t have to be billed separately nor does the part of your home have to be set aside permanently for business. For example, you can claim for allowable expenses for a room used as your office during work hours, but it must not be used for other purposes during that time.
VAT accounting schemes can make your life easier, simplifying your VAT accounting and in some cases improving your cashflow. If your taxable turnover of standard and reduced-rated supplies is below £1.35m (excluding VAT), or if you are involved in retail or selling second-hand goods, a VAT accounting scheme could suit you.